Paging apparatus and method in a mobile communication system providing multimedia broadcast multicast service

ABSTRACT

A paging apparatus and method in a mobile communication system providing an MBMS (Multimedia Broadcast Multicast Service). In the mobile communication system, to page a UE for a first service through a primary carrier during a second service in progress through a secondary carrier, a PICH (Paging Indication Channel) transmitter in a Node B transmits paging indication information to the UE through the primary carrier by oscillating the primary carrier as a transmission frequency. A PCH (Paging Channel) transmitter transmits paging information to the UE through the primary carrier or the secondary carrier by oscillating the primary carrier or the secondary carrier as the transmission frequency under a predetermined control. A PBMSCH (Physical Broadcast Multicast Shared Channel) transmitter transmits data of the second service through the secondary carrier by oscillating the secondary carrier as the transmission frequency. A controller controls the primary carrier or the secondary carrier to be oscillated as the transmission frequency of the PCH transmitter if the paging indication information indicates paging.

PRIORITY

This application is a continuation of U.S. application Ser. No.12/605,070, which is a continuation of U.S. application Ser. No.10/274,565, which claims priority to an application entitled “PagingApparatus and Method in a Mobile Communication System ProvidingMultimedia Broadcast Multicast Service” filed in the Korean IndustrialProperty Office on Oct. 20, 2001 and assigned Serial No. 2001-64966, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a mobile communicationsystem, and in particular, to a paging apparatus and method in a mobilecommunication system providing an MBMS (Multimedia Broadcast MulticastService).

2. Description of the Related Art

CDMA (Code Division Multiple Access) generally uses a plurality ofphysical channels. The physical channels are common channels anddedicated channels. The common channels are shared among a plurality ofUEs (User Equipments) within a cell area of a Node B, and the dedicatedchannels are assigned to particular UEs by the Node B. The commonchannels include a CPICH (Common Pilot Channel), a P-CCPCH (PrimaryCommon Control Physical Channel), an S-CCPCH (Secondary Common ControlPhysical Channel), and a PICH (Paging Indicator Channel). The dedicatedchannels include a DPCH (Dedicated Physical channel).

In CDMA, broadcasting channels broadcast information to UEs. There aredifferent broadcasting channels in a CDMA mobile communication system,for example, in a Release 99 mobile communication system. They are a BCH(Broadcasting Channel) and an FACH (Forward Access Channel). The BCHbroadcasts SI (System Information) required for cell access to UEs, andthe FACH sends control information about assignment of a dedicatedchannel and a broadcast message to a particular UE in addition to thefunction of the BCH. Since the main use of the broadcasting channels isto deliver common control information to UEs and control information toa particular UE, transmission of user data on the broadcasting channelsis limited.

Recently, the development of communication technology has brought withit multicast multimedia communication that enables transmission of alarge amount of data, such as packet data and circuit data, in additionto voice service in CDMA mobile communication systems. Thus manymulticast multimedia applications have been proposed. Particularly, theMBMS has emerged as a future generation mobile communication service.The MBMS is a service that provides audio data and video datacontemporaneously. Since the MBMS requires a large amount oftransmission resources and is likely to cause concurrent provision ofdifferent services within a Node B on a large scale, it is provided onbroadcasting channels. BMC (Broadcast Multicast Control), a singlechannel sharing technique, is free of constraints of temporal delaysince it is applied to low rate transmission such as text broadcasting.As compared to the BMC, the MBMS is provided at a very high data rateand is sensitive to temporal delay. Therefore, the MBMS must be servicedin a different way from the BMC.

When transmitting a signal on a radio channel, the signal is modulatedwith a carrier having a higher frequency than the signal itself prior totransmission in order to improve transmission characteristics againstexternal noise in a typical mobile communication system. Hence, theconventional CDMA mobile communication system sends physical channelsavailable to a Node B with one carrier. In other words, both commonchannels and dedicated channels are transmitted with one carrier.However, resources are not sufficient to provide existing services inthe conventional CDMA mobile communication system. Accordingly, it isobvious that the provision of the MBMS will lead to a further lack ofresources.

In this context, studies have been conducted on a solution to the lackof resources to support the future generation mobile communicationsystem requiring a large amount of resources.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide anapparatus and method for providing an MBMS through an additional carrierin a mobile communication system.

It is another object of the present invention to provide an apparatusand method for carrying out wireless communication through a pluralityof carriers between a Node B and a UE in a mobile communication system.

It is a further object of the present invention to provide an apparatusand method for providing different services by switching carriers whenthe services are provided using a plurality of carriers.

It is still another object of the present invention to provide a pagingapparatus and method in a mobile communication system providingdifferent services through a plurality of carriers.

To achieve the above and other objects, a Node B provides a firstservice through a primary carrier to a first UE within its cell area anda second service to at least two UEs including the first UE through asecondary carrier having a different frequency from the primary carrier.To page the first UE during the second service in progress through thesecondary carrier, a PICH (Paging Indicator Channel) transmittertransmits paging indication information to the first UE through theprimary carrier by oscillating the primary carrier as a transmissionfrequency. A PCH (Paging Channel) transmitter transmits paginginformation to the first UE through the primary carrier or the secondarycarrier by oscillating the primary carrier or the secondary carrier asthe transmission frequency under a predetermined control. A PBMSCH(Physical Broadcast Multicast Shared Channel) transmitter transmits dataof the second service through the secondary carrier by oscillating thesecondary carrier as the transmission frequency. A controller controlsthe primary carrier or the secondary carrier to be oscillated as thetransmission frequency of the PCH transmitter if the paging indicationinformation indicates paging.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 schematically illustrates a system configuration for providing anMBMS through a plurality of carriers in a CDMA mobile communicationsystem according to the present invention;

FIG. 2 illustrates a PBMSCH (Physical Broadcast Multicast SharedChannel) slot format according to the present invention;

FIG. 3 schematically illustrates a typical PICH structure;

FIG. 4 is a flowchart illustrating a paging procedure during an MBMS inprogress through a secondary carrier according to an embodiment of thepresent invention;

FIG. 5 is a flowchart illustrating a paging procedure during an MBMS inprogress through a secondary carrier according to another embodiment ofthe present invention;

FIG. 6 is a flowchart illustrating a paging procedure during an MBMS inprogress through a secondary carrier according to a third embodiment ofthe present invention;

FIG. 7 is a block diagram of a transmitter for transmittingsecondary-carrier signals to implement paging according to theembodiments of the present invention;

FIG. 8 is a block diagram of a transmitter for transmittingprimary-carrier signals to implement paging according to the embodimentsof the present invention;

FIG. 9 is a block diagram of PICH generation units illustrated in FIGS.7 and 8;

FIG. 10 is a block diagram of PCH generation units illustrated in FIGS.7 and 8;

FIG. 11 is a block diagram of a receiver to implement paging accordingto the embodiments of the present invention; and

FIG. 12 is a diagram illustrating a signal flow for paging between aNode B and a UE receiving the MBMS through a secondary carrier.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described hereinbelow with reference to the accompanying drawings. In the followingdescription, well-known functions or constructions are not described indetail since they would obscure the invention in unnecessary detail.

It is to be noted that the present invention pertains to providing anMBMS in a CDMA mobile communication system. The MBMS provides amultimedia service to all UEs via one broadcasting channel in the CDMAmobile communication system, thus maximizing channel efficiency andincreasing use efficiency of resources. As a result, a high qualityservice is available at a low cost.

The present invention is realized by transmitting a PBMSCH (PhysicalBroadcast Multicast Shared Channel) with an additional secondarycarrier. Thus, a method of receiving a conventional CDMA service througha primary carrier and an MBMS through a secondary carrier in a UE isprovided. The present invention also provides a method of paging throughthe secondary carrier to perform a conventional service when the pagingis generated during the MBMS in progress through the secondary carrier.

FIG. 1 schematically illustrates a system configuration for providing anMBMS through a plurality of carriers in a CDMA mobile communicationsystem according to the present invention. Referring to FIG. 1, a Node B101 sends a conventional common channel and a dedicated channel incombination through a primary carrier f₁ 102 and provides an MBMSthrough a secondary carrier f₂ 103. The common and dedicated channelsinclude a CPICH, a P-CCPCH, an S-CCPCH, a PICH, and a DPCH. A PBMSCH andan S-CPICH (Secondary Common Pilot Channel) are transmitted through thesecondary carrier f₂ 103. The PBMSCH is a physical channel for providingthe MBMS. The S-CPICH is required for phase reference when a carrier ischanged. A slot format for the PBMSCH will be described below withreference to FIG. 2.

FIG. 2 illustrates a format of a PBMSCH slot according to the presentinvention. Referring to FIG. 2, reference numeral 201 denotes a radioframe. One radio frame 201 includes 15 slots (slot #0-slot #14). Theslots are same in structure. Slot #i 202 is taken as beingrepresentative of the slots. Slot #i 202 delivers only data,specifically multiplexed BMSCH (Broadcast Multicast Shared Channel)data. An SF (Spreading Factor) varies with the bit rates of servicesprovided through BMSCHs and thus determines the number of bits perPBMSCH slot. The PBMSCH is a physical channel to which the BMSCHs,transport channels, are mapped.

A PBMSCH transmitting method for the MBMS disclosed in the presentinvention is compatible with services provided in the existing systems.As illustrated in FIG. 1, a UE 105 receives one carrier signal in apredetermined period. When channels for providing conventional servicesare transmitted through the primary carrier signal f₁ 102 and the PBMSCHis transmitted through the secondary carrier signal f₂ 103, frequencyswitching 104 occurs depending on which carrier the UE 105 receives.Therefore, the UE 105 must receive a new service, MBMS by frequencyswitching between the two carriers without adversely influencing theconventional services. In this context, the present invention proposes afrequency switching method providing a new service through a differentcarrier during an existing service in progress.

In the present invention, frequency switching occurs in two situations.In the first, the UE must receive a radio signal through the secondarycarrier to receive the MBMS during receiving a radio signal through theprimary carrier. In the other, the UE terminates the MBMS or mustreceive a radio signal through the primary carrier for a new voice callor a new service.

In the former situation, if the UE does not receive another serviceduring receiving a radio signal through the primary carrier, it switchesto the secondary carrier through an initial setup for the MBMS. In thelatter situation, when the UE intentionally terminates the ongoing MBMS,it switches from the primary carrier to the secondary carrier. Theseoperations are rather simple. However, when the UE receives a requestfor a service through the primary carrier, such as a voice call from aNode B during the MBMS in progress, it must be able to receive a pagingsignal from the Node B. The Node B must notify the UE that the UE is toreceive the service through the primary carrier by sending a pagingsignal. In other words, the UE must receive paging information duringthe MBMS in progress through the secondary carrier.

Now, the paging will be described. When the UE uses only the primarycarrier, it periodically monitors a PICH signal from the Node B andchecks whether there is a PCH (Paging Channel) destined for the UE.Information about the PICH is contained in an SIB (System InformationBlock) #5 of a PCH. The UE acquires the PICH information and receivesthe PICH signal by checking the PCH.

FIG. 3 illustrates a structure of the PICH. Referring to FIG. 3, oneradio frame 303 is 10 ms in duration and has 300 bits (b₀ to b₂₉₉). 288paging indicator bits are b₀ to b₂₈₇ in an area 301, and a 12-bit area302 (b₂₈₈ to b₂₉₉) is reserved for future use.

Paging by the paging indicators in the area 301 of the radio frame 303is expressed in Eq. (1) and Table 1.

$\begin{matrix}{q = {\left( {{PI} + \left\lfloor {\begin{pmatrix}\left( {18 \times \left( {{SFN} +} \right.} \right. \\{\left\lfloor {{SFN}/18} \right\rfloor +} \\{\left\lfloor {{SFN}/64} \right\rfloor +} \\\left. \left\lfloor {{SFN}/512} \right\rfloor \right)\end{pmatrix}{{mod}144} \times \frac{N_{p}}{144}} \right\rfloor} \right){mod}\; N_{p}}} & (1)\end{matrix}$where PI is a parameter from a higher layer, SFN (System Frame Number)is frame timing information counted by a Node B, and N_(p) is the numberof paging indicators per frame. q is determined from SFN, N_(p), and PI,which are set for a UE at a given time. According to q, the positions ofpaging indicator bits assigned to the UE are determined. Table 1illustrates mapping of a paging indicator Pq of a PICH, PICH b_(i).

TABLE 1 Number of paging indicators per frame (N_(p)) P_(q) = 1 P_(q) =0 N_(p) = 18 {b_(16q), . . . , b_(16q+15)} = {−1, {b_(16q), . . . ,b_(16q+15)} = {+1, −1, . . . , −1} +1, . . . , +1} N_(p) = 36 {b_(8q), .. . , b_(8q+7)} = {b_(8q), . . . , b_(8q+7)} = {−1, −1, . . . , −1} {+1,+1, . . . , +1} N_(p) = 72 {b_(4q), . . . , b_(4q+3)} = {b_(4q), . . . ,b_(4q+3)} = {−1, −1, . . . , −1} {+1, +1, . . . , +1} N_(p) = 144{b_(2q), . . . , b_(2q+1)} = {b_(2q), . . . , b_(2q+1)} = {−1, −1, . . ., −1} {+1, +1, . . . , +1}

If the paging indicator bits are all −1s in Table 1, this implies thatthe UE must read a PCH. On the other hand, if they are all +1s, thisimplies that the UE does not need to read the PCH. The basic concept ofpaging is to read an S-CCPCH containing a PCH according to pagingindicator bits determined according to the parameter q. The S-CCPCH is aphysical channel to which a PCH being a transport channel is mapped.

Since it is determined whether the PCH is to be read or not by the aboveUE grouping, more than one UE may use the same paging indicator. In thiscase, despite receiving a paging indicator on a PICH, neither of the UEsmay be wanted for paging on a PCH of the S-CCPCH.

The above paging occurs when all services are provided through a singlecarrier in the conventional technology. Meanwhile, the present inventionpertains to paging when two carriers are used to provide two differentservices. That is, a UE receives a conventional service such as voiceservice through the primary carrier and an MBMS on a PBMSCH through thesecondary carrier.

First Embodiment

In accordance with a first embodiment of the present invention, in orderto enable paging during an MBMS in progress through the secondarycarrier, a PICH and an S-CCPCH are used for paging through the secondarycarrier. While the PICH and S-CCPCH are transmitted through the primarycarrier, they are also assigned to the second carrier, so that a UE canmonitor the PICH through the secondary carrier and check pagingindication information during receiving a PBMSCH signal through thesecondary carrier. If the paging indication information orders the UE toreceive a PCH signal, the UE receives a PCH signal on the S-CCPCHthrough the secondary carrier and determines whether it is paged.

Transition to a primary-carrier service by receiving the PICH and thePCH during receiving a PBMSCH signal through the secondary carrier willbe described with reference to FIG. 4.

FIG. 4 is a flowchart illustrating a paging procedure during an MBMS inprogress through a secondary carrier according to the first embodimentof the present invention. Referring to FIG. 4, a UE receives a PBMSCHsignal from a Node B through a secondary carrier in step 401. In step402, the UE periodically monitors a PICH through the secondary carrierduring receiving a PBMSCH signal, analyzes the PICH signal, and reads apaging indicator from the PICH. The UE determines whether the pagingindicator orders the UE to receive a PCH in step 403. If the pagingindicator is −1, this implies that the UE is to receive a PCH signal andif the paging indicator is +1, the UE does not need to receive the PCHsignal. In the latter case, the UE returns to step 401. In the formercase, the UE receives an S-CCPCH signal as well as the PBMSCH signalthrough the secondary carrier and reads a PCH from the S-CCPCH in step404. Then, the UE determines whether paging information set in the PCHis for it in step 405. If the paging information is not for the UE, theUE returns to step 401. On the contrary, if the paging information isdestined for the UE, the UE establishes a path from which a radiochannel signal can be received from the Node B through a primary carrierby frequency switching in step 406. The path establishment is carriedout by switching the reception frequency of the UE from the secondarycarrier to the primary carrier. In step 407, the UE receives a targetchannel signal among radio channel signals transmitted from the Node Bthrough the primary carrier.

In accordance with the first embodiment of paging, the PICH and PCH aretransmitted through the secondary carrier as well as through the primarycarrier, so that the UE can receive paging information during receivinga PBMSCH signal through the secondary carrier. However, transmission ofthe same paging information through the two carriers decreases theefficiency of channel resources. To improve the channel resourcesefficiency, a second embodiment of paging is proposed.

Second Embodiment

In a second embodiment of the present invention, the PICH isadditionally assigned to the secondary carrier for paging, which alreadyincludes the PBMSCH and the S-CPICH. While receiving a PBMSCH signalthrough the second carrier, a UE periodically monitors the PICH throughthe second carrier and reads paging indication information. If thepaging indication information indicates paging, the UE temporarilydiscontinues reception of the PBMSCH signal, receives an S-CCPCH throughthe primary carrier by frequency switching, and reads a PCH from theS-CCPCH to determine whether it is paged.

Transition to a primary-carrier service by receiving the PICH whilereceiving the PBMSCH signal through the secondary carrier and thenreceiving the PCH through the primary carrier will be described withreference to FIG. 5.

FIG. 5 is a flowchart illustrating a paging procedure during an MBMS inprogress through the secondary carrier according to the secondembodiment of the present invention. Referring to FIG. 5, a UE receivesa PBMSCH signal from a Node B through a secondary carrier in step 501.In step 502, the UE periodically monitors a PICH through the secondarycarrier while receiving the PBMSCH signal, analyzes the PICH, and readsa paging indicator from the PICH. The UE determines whether the pagingindicator orders the UE to receive a PCH in step 503. If the pagingindicator does not indicate paging, the UE returns to step 501. If thepaging indicator indicates paging, the UE establishes a path from whichradio channel signals can be received from the Node B through theprimary carrier by frequency switching in step 504. The pathestablishment is carried out by switching the UE's reception frequencyfrom the secondary carrier to the primary carrier. In step 505, the UEreceives an S-CCPCH through the primary carrier and reads a PCH signalfrom the S-CCPCH.

In step 506, the UE determines the whether paging information set in thePCH is destined for it. If the paging information is not for the UE, theUE establishes a path by frequency switching, enabling the PBMSCH signalto be received through the secondary carrier in step 507 and returns tostep 501. The path establishment is carried out by switching thereception frequency from the primary carrier to the secondary carrier.If the paging information is for the UE, the UE receives a targetchannel signal among radio channel signals transmitted from the Node Bthrough the primary carrier in step 508.

In accordance with the second embodiment of paging, while the PICHsignal is transmitted through the secondary carrier, the S-CCPCHincluding the PCH is transmitted through the primary carrier. Therefore,the problem of decreased channel resource efficiency as encountered inthe first embodiment of paging is solved. Despite the advantage,however, mapping of paging indicators by grouping all UEs may lead toincorrect paging indication to some UEs. In this case, unnecessaryfrequency switching from the secondary carrier to the primary carrierand the opposite occurs twice to the UEs. During the frequencyswitching, reception of the PBMSCH signal is discontinued. As a result,MBMS efficiency is decreased. A third embodiment of paging according tothe present invention is devised in order to overcome the limitations interms of MBMS efficiency and channel resources efficiency.

Third Embodiment

As in the second embodiment of paging, the PICH as well as the PBMSCHand the S-CPICH are transmitted through the secondary carrier. Whilereceiving the PBMSCH signal through the second carrier, a UEperiodically monitors the PICH through the second carrier and readspaging indication information. If the paging indication informationindicates paging, the UE temporarily discontinues reception of thePBMSCH signal, receives an S-CCPCH through the primary carrier byfrequency switching, and reads a PCH signal from the S-CCPCH todetermine whether it is paged. The third embodiment is different fromthe second embodiment in that the PICH signal is transmitted only to UEsthat are receiving PBMSCH signals from a Node B. Paging indicator bitsare mapped to the PICH by Eq. (1) or directly mapped to a physicalchannel without an information signal from a higher layer.

Transition to a primary-carrier service by receiving the PICH signal,which a Node B transmits only to UEs currently receiving an MBMS data,while receiving the PBMSCH signal through the secondary carrier and thenreceiving the PCH signal through the primary carrier will be describedwith reference to FIG. 6.

FIG. 6 is a flowchart illustrating a paging procedure during an MBMS inprogress through the secondary carrier according to the third embodimentof the present invention.

Referring to FIG. 6, when a UE is to receive MBMS data through thesecondary carrier while receiving a target channel signal through theprimary carrier, it initially sets up the PBMSCH and the PICH in step601. In step 602, the UE establishes a path from which the PBMSCH signalcan be received from the Node B through the secondary carrier byfrequency switching. The path establishment is carried out by switchinga UE's reception frequency from the primary carrier to the secondarycarrier. The UE receives the PBMSCH signal from the Node B through thesecondary carrier in step 603. The UE periodically monitors the PICHdirected to particular UEs through the secondary carrier duringreceiving the PBMSCH signal, analyzes the PICH signal, and reads apaging indicator in step 604. The UE analyzes the paging indicator anddetermines whether the paging indicator orders the UE to receive a PCHaccording to the value of the paging indicator in step 605. If thepaging indicator does not indicate paging, the UE returns to step 603.If the paging indicator indicates paging, the UE establishes a path byfrequency switching, enabling radio channel signals to be received fromthe Node B through the primary carrier in step 606. The pathestablishment is carried out by switching the reception frequency fromthe secondary carrier to the primary carrier. Then, the UE receives anS-CCPCH signal through the primary carrier and reads a PCH signal fromthe S-CPCCH in step 607. In step 608, the UE determines whether paginginformation in the PCH signal is destined for it. If the paginginformation is not for the UE, the UE establishes the path for receivingthe PBMSCH signal through the secondary carrier by frequency switchingin step 609 and returns to step 603. The path establishment is carriedout by switching the reception frequency from the primary carrier to thesecondary carrier. If the paging information is for the UE, the UEreceives a target channel signal among radio channel signals transmittedfrom the Node B through the primary carrier in step 610.

In accordance with the third embodiment of paging, paging indicators aremapped on the PICH only for particular UEs using the secondary carrier.The maximum number of UEs that can receive an MBMS data through thesecondary carrier is equal to or less than that of paging indicatorsthat can be mapped on the PICH. Therefore, the Node B assigns oneavailable paging indicator bits to a UE that initiates an MBMS. Thenumber of UEs that can receive the MBMS can be increased by using morePICHs.

The problem of decreased channel resource efficiency as encountered inthe first embodiment of paging is solved by checking paging informationon the PCH through the primary carrier, and the problem of unnecessaryfrequency switching and the resulting decreased service efficiency asencountered in the second embodiment of paging is solved by limitingtransmission of the PICH only to UEs that are currently receiving theMBMS.

A description will be made below of a transmitter and a receiver forimplementing the above-described paging in the CDMA mobile communicationsystem according to the embodiments of the present invention.

FIG. 7 is a block diagram of a transmitter for transmittingsecond-carrier signals to implement paging according to the embodimentsof the present invention. Referring to FIG. 7, a serial to parallelconverter (SPC) 702 converts MBMS data 701 to parallel I and Q channelsignals for QPSK (Quadrature Phase Shift Keying) modulation and feedsthe I and Q channel signals to multipliers 704 and 705, respectively.The multipliers 704 and 705 multiply the I and Q channel signals by achannelzation code C_(OVSF) _(—) _(PBMSCH) 703 assigned to a PBMSCH,respectively. A multiplier 706 multiplies the Q channel signal receivedfrom the multiplier 705 by a signal j, for a 90° phase shift. An adder707 adds the outputs of the multipliers 704 and 706. A multiplier 708multiplies a signal received from the adder 707 by a predeterminedchannel gain 709 and feeds the product to a multiplexer (MUX) 711. Whenthere are a plurality of PBMSCHs, as many sets of the devices 701 to 708and the channel gain 709 as the number of the PBMSCHs are required. Theresulting PBMSCH signals are fed to the MUX 711.

A PICH generation unit 720 generates a PICH signal containing pagingindicator bits for UEs within a Node B. A multiplier 721 multiplies thePICH signal by a predetermined channel gain g_(PICH) 722, for channelcompensation. A PCH generation unit 723 generates a PCH signalcontaining paging information for each UE within the Node B. Amultiplier 724 multiplies the PCH signal by a predetermined channel gaing_(PCH) 725, for channel compensation.

The MUX 711 multiplexes the PBMSCH signal, the PICH signal, and the PCHsignal. A multiplier 713 multiplies the output of the MUX 711 by apredetermined scrambling code C_(SCRAMBLE) 712. Thus the multiplier 713acts as a scrambler. A multiplier 715 multiplies the scrambled signal bya predetermined channel gain 714. A modulator 716 modulates the outputof the multiplier 715 with the secondary carrier. An RF (Radiofrequency) processor 717 converts the modulation signal to an RF signaltransmittable in the air. The RF signal is transmitted in the air via anantenna 718.

While the transmitter transmits the PBMSCH signal, PICH signal, and PCHsignal (i.e., S-CCPCH) through the secondary carrier according to thefirst embodiment of the present invention, transmitters for transmittingthe PBMSCH and the PICH through the secondary carrier according to thesecond and third embodiments of the present invention can be realized byomitting the PCH generation unit 723 and the multiplier 724.

Alternatively, transmitters for performing the paging proceduresaccording to the first, second, and third embodiments of the presentinvention can be implemented by appropriate control of the MUX 711. Forpaging according to the first embodiment, the MUX 711 multiplexes allinput signals. For paging according to the second and third embodiments,the MUX 711 multiplexes only the PBMSCH and the PICH signals.

FIG. 8 is a block diagram of a transmitter for transmittingprimary-carrier signals to implement the paging according to theembodiments of the present invention. Referring to FIG. 8, a PICHgeneration unit 750 generates a PICH signal containing paging indicatorbits for UEs within the Node B. A multiplier 752 multiplies the PICHsignal by a predetermined channel gain g_(PICH) 751, for channelcompensation. A PCH generation unit 753 generates a PCH signalcontaining paging information for each UE within the Node B. Amultiplier 754 multiplies the PCH signal by a predetermined channel gaing_(PCH) 755, for channel compensation.

A MUX 757 multiplexes the outputs of the multipliers 752 and 754. Amultiplier 759 multiplies the output of the MUX 757 by a predeterminedscrambling code C_(SCRAMBLE) 758. Thus the multiplier 759 acts as ascrambler. A multiplier 761 multiplies the scrambled signal by apredetermined channel gain 760. A MUX 763 multiplexes the output of themultiplier 761 and other input signals 762 scrambled with differentscrambling codes. A modulator 764 modulates the output of the MUX 763with the primary carrier. An RF processor 765 converts the modulationsignal to an RF signal transmittable in the air. The RF signal istransmitted in the air via an antenna 766.

While pairs of the PICH generation units 720 and 750, the PCH generators723 and 753, and the antennas 718 and 766 each are separatelyillustrated in FIGS. 7 and 8, each pair can be integrated into onesingle device.

FIG. 9 is a block diagram of the PICH generation units illustrated inFIGS. 7 and 8. Referring to FIG. 9, a serviced UE determiner 801 feedscontrol information from a higher layer, including information about UEsthat are currently being serviced, to a controller 802. A pagingindicator position controller 802 controls the position of a pagingindicator for each UE according to the control information. A PICHgenerator 803 generates a PICH signal according to information receivedfrom the paging indicator position controller 802. An SPC 804 convertsthe PICH signal to parallel I and Q channel signals. A multiplier 806multiplies the I channel signal by a PICH channelization code_(COVSF)_(—) _(PICH) 1805. A multiplier 807 multiplies the Q channel signal bythe PICH channelization code_(COVSF) _(—) _(PICH) 805. A multiplier 808multiplies the output of the multiplier 807 by a signal j to shift thephase of the Q channel signal by 90°. An adder 809 adds the outputs ofthe multipliers 806 and 808, thereby combining the I and Q channelsignals. The combined signal is fed to the multiplier 721 illustrated inFIG. 7 and the multiplier 752 illustrated in FIG. 8.

Meanwhile, the serviced UE determiner 801 is not required in the firstand second embodiments but is needed in the third embodiment becausePICH grouping varies according to the carriers. The same pagingindicator position controller 802 can be applied to the PICH generationunits 720 and 750 illustrated in FIGS. 7 and 8 since a paging indicatorposition control is performed in the same manner in the first and secondembodiments. However, different paging indicator position controls arecarried out according to carriers in the PICH generation units 720 and750 in the third embodiment of the present invention.

FIG. 10 is a block diagram of the PCH generators 723 and 753 illustratedin FIGS. 7 and 8. Referring to FIG. 10, a PCH generator 821 generates aPCH signal and a MUX 822 multiplexes the PCH signal. An S-CCPCHgenerator 823 maps the PCH signal to an S-CCPCH signal. An SPC 824separates the S-CCPCH signal to I and Q channels signals, for QPSKmodulation. A multiplier 825 multiplies the I channel signal by apredetermined PCH channelization code C_(OVSF) _(—) _(S-CCPCH) and amultiplier 826 multiplies the Q channel signal by the PCH channelizationcode C_(OVSF) _(—) _(S-CCPCH). A multiplier 828 multiplies the output ofthe multiplier 826 by a signal j to shift the phase of the Q channelsignal by 90°. An adder 829 adds the outputs of the multipliers 826 and828, thereby combining the I and Q channel signals. The combined signalis fed to the multiplier 724 illustrated in FIG. 7 and the multiplier754 illustrated in FIG. 8.

FIG. 11 is a block diagram of a receiver according to the presentinvention. Referring to FIG. 11, an RF processor 902 converts an RFsignal received through an antenna 901 to a baseband signal. A filter903, which is connected to an oscillator 956, filters the basebandsignal using a frequency generated in the oscillator 956. Theoscillation frequency generated from the oscillator 956 is controlled byan oscillator controller 955. A multiplier 904 descrambles the output ofthe filter 903 by multiplying it by the same scrambling code as used inthe transmitter. Thus the multiplier 904 acts as a descrambler. A DEMUX(demultiplexer) 905 demultiplexes the descrambled signal into a PICHsignal, a PCH signal, a PBMSCH signal, and other signals under thecontrol of a controller 954.

A complex to I/Q stream block 906 separates the PICH signal into I and Qchannel signals. A multiplier 907 multiplies the Q channel signalreceived from the complex to I/Q stream block 906 by a signal j, therebyconverting the Q channel signal to a real number signal. A multiplier908 multiplies the Q channel signal received from the multiplier 907 bya PICH channelization code C_(OVSF) _(—) _(PICH) as used for the PICH inthe transmitter, and a multiplier 909 multiplies the I channel signalreceived from the complex to I/Q stream block 906 by the PICHchannelization code C_(OVSF) _(—) _(PICH) . A parallel-to-serialconverter (PSC) 911 converts the outputs of the multipliers 908 and 909to a serial signal. A PICH generator 912 generates a PICH signal fromthe output of the PSC 911. A paging indication determiner 913 determineswhether the PICH signal indicates paging.

A complex to I/Q stream block 921 separates the PCH signal into I and Qchannel signals. A multiplier 922 multiplies the Q channel signalreceived from the complex to I/Q stream block 921 by the signal j,thereby converting the Q channel signal to a real number signal.Multipliers 924 and 925 respectively multiply the I channel signalreceived from the complex to I/Q stream block 921 and the Q channelsignal received from the multiplier 922 by an S-CCPCH channelizationcode C_(OVSF) _(—) _(S-CCPH) as used for the S-CCPCH in the transmitter.A PSC 926 converts the outputs of the multipliers 924 and 925 to aserial signal. An S-CCPCH generator 927 generates an S-CCPCH signal fromthe output of the PSC 926. A DEMUX 928 demultiplexes the S-CCPCH signal.A PCH generator 929 generates a PCH signal from the output of the DEMUX928. A paging determiner 930 checks paging information from the PCHsignal.

A complex to I/Q stream block 931 separates the PBMSCH signal into I andQ channel signals. A multiplier 932 multiplies the Q channel signalreceived from the complex to I/Q stream block 931 by a signal j, therebyconverting the Q channel signal to a real number signal. A multiplier934 multiplies the I channel signal received from received from thecomplex to I/Q stream block by a PBMSCH channelization code C_(OVSF)_(—PBMSCH) as used for the PBMSCH in the transmitter, and a multiplier935 multiplies the Q channel signal received from the multiplier 932 bythe PBMSCH channelization code C_(OVSF) _(—) _(PBMSCH). A PSC 936converts the outputs of the multipliers 934 and 935 to a serial signal.A PBMSCH generator 937 generates a PBMSCH signal from the output of thePSC 936. Thus, the receiver receives an MBMS.

In the first embodiment of paging, when the paging indication determiner913 determines that there is a paging indication, the controller 954controls the DEMUX 905 to output the S-CCPCH signal, specifically thePICH signal. When the PCH signal is acquired, the paging determiner 930then determines whether the UE is paged. If it is paged, the pagingdeterminer 930 drives the oscillator controller 955, notifying thepaging. The oscillator controller 955 controls the oscillator 956 togenerate the primary or secondary carrier selectively. Under the controlof the oscillator controller 955, frequency switching is carried outbetween the primary carrier and the secondary carrier using theoscillator 956.

In the second embodiment of paging, when the paging indicationdeterminer 913 determines that there is a paging indication, it notifiesthe oscillator controller 955 of the paging indication. The oscillatorcontroller 955 then controls the oscillator 956 to perform frequencyswitching between the primary carrier and the secondary carrier.

In the third embodiment of paging, signal processing is performed in thesame manner as in the second embodiment except that the pagingindication determiner 913 determines whether there is a pagingindication in a different manner depending on the primary carrier or thesecondary carrier.

The operations of a Node B and a UE in relation to an MBMS through thesecondary carrier will be described referring to FIG. 12.

FIG. 12 is a diagram illustrating a signal flow for providing an MBMSfrom a Node B to a UE through the secondary carrier according to thepresent invention. Referring to FIG. 12, the Node B transmits PICH andPCH signals through the primary carrier in step 1001. Meanwhile, the UEreceives cell information from a cell that it belongs to as it issearched for by a cell search when power is on in step 1021 andtransmits a UE registration request to the Node B in step 1051. Uponreceipt of the UE registration request during transmission the PICH andPCH signals, the Node B registers the new UE in step 1002. In step 1003,the Node B generates PI information for paging the UE and transmits thePICH signal to the UE in correspondence to the PI information.Contemporaneously, the Node B transmits the new PI information to the UEin step 1052 and transmits the resulting PICH update signal through theprimary carrier in step 1053. The UE monitors the PICH periodically andobtains paging information. Meanwhile, upon request for an MBMS from auser in step 1023, the UE transmits the MBMS request to the Node B andthe Node B registers the requesting UE in an MBMS receiving UE list instep 1004. The Node B generates PBMSCH control information to the UE instep 1005 and the UE receives the control information and thus a PBMSCHsignal in step 1024. While an RNC (Radio Network Controller) actuallycontrols registration for the MBMS and transmission of the PBMSCHcontrol information, a description of an MBMS-related operation betweenthe Node B and the RNC will not be provided here for convenience. ThePBMSCH control information may contain information about the frequencyand physical channel code of the PBMSCH.

Since the Node B transmits the PBMSCH signal through the secondarycarrier in step 1055, the PICH and PCH signals need to be transmittedthrough the secondary carrier simultaneously. In the first and secondembodiments of paging, the PICH update transmitted in step 1053 is alsotransmitted through the secondary carrier. Therefore, the Node B adoptsthe same PI, SFN, N_(p) parameters. On the other hand, in the thirdembodiment of paging, since the PICH is confined to UEs that arereceiving secondary-carrier signals, the Node B updates the PICHaccording to paging indicator positions for the UEs registered for theMBMS in step 1006. The paging indicator position information is alsotransmitted to the UE in step 1057. Then the UE can receive the PICHsignal through the secondary carrier. Consequently, the UE can be pagedduring the MBMS in progress through the secondary carrier in order toreceive a channel signal through the primary carrier.

In accordance with the present invention, it is possible to page a UEwhile an MBMS is in progress through a secondary carrier in order toprovide an existing service through a primary carrier in a mobilecommunication system supporting the MBMS. Such paging maximizes theefficiency of radio transmission resources and removes errors involvedwith paging by UE grouping.

While the invention has been shown and described with reference tocertain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

1. A method of receiving, at a UE (User Equipment), paging for a firstservice while a second service, different from the first service, is inprogress in a mobile communication system, the method comprising:providing, to the UE, the first service through a primary carrier;providing, to the UE, the second service through a secondary carrierhaving a different frequency from the primary carrier; receiving, by theUE, paging indication information for the first service through thesecondary carrier while receiving the second service through thesecondary carrier; receiving, by the UE, paging information for thefirst service through the secondary carrier in response to the receivedpaging indication information; and receiving, by the UE, the firstservice through the primary carrier by switching a reception frequencyof the UE from the secondary carrier to the primary carrier in responseto the paging information received through the secondary carrier,wherein the UE reads the primary carrier based on the paging informationreceived through the secondary carrier.
 2. The method of claim 1,wherein the first service has a higher priority than the second service.3. The method of claim 1, wherein the paging information is transmittedto UEs that are receiving the second service.
 4. A method of receiving,at a UE (User Equipment), paging for a first service while a secondservice, different from the first service, is in progress in a mobilecommunication system, the method comprising: providing, to the UE, thefirst service through a primary carrier; providing, to the UE, thesecond service through a secondary carrier having a different frequencyfrom the primary carrier; receiving paging information for the firstservice through the secondary carrier while receiving the second servicethrough the secondary carrier; and receiving the first service throughthe primary carrier by switching a reception frequency of the UE fromthe secondary carrier to the primary carrier in response to the paginginformation received through the secondary carrier, wherein the UE readsthe primary carrier based on the paging information received through thesecondary carrier.
 5. The method of claim 4, wherein the first servicehas a higher priority than the second service.
 6. The method of claim 4,wherein the paging information is transmitted to UEs that are receivingthe second service.
 7. An apparatus of receiving, at a UE (UserEquipment), paging for a first service while a second service, differentfrom the first service, is in progress in a mobile communication system,wherein the first service is provided through a primary carrier and thesecond service is provided through a secondary carrier, the secondarycarrier having a different frequency from the primary carrier, theapparatus comprising: a first receiver being adapted to receive paginginformation for the first service through the secondary carrier whilereceiving the second service through the secondary carrier byoscillating the primary carrier or the secondary carrier as a receptionfrequency; a second receiver being adapted to receive the first servicethrough the primary carrier by switching a reception frequency of the UEfrom the secondary carrier to the primary carrier in response to thepaging information received through the secondary carrier; and acontroller for controlling the primary carrier or the secondary carrierto be oscillated as the reception frequency of the first receiver if theUE receives paging information, wherein the UE reads the primary carrierbased on the paging information received through the secondary carrier.8. The method of claim 7, wherein the paging information is transmittedto UEs that are receiving the second service.